Influence of the mean stress on the fatigue life of welded joints under variable amplitude loading

The effect of the mean stress on the fatigue life of welded joints fabricated with three different plate thicknesses was investigated under variable amplitude (VA) loading. Test results indicate that Miner's sum, D, at failure increases as reducing the mean stress in the VA loading; hence, limiting D to 0.5, as advised in the fatigue design codes, may be unduly conservative in the fatigue assessment. The joint with a thinner plate is tend to have a better fatigue performance. New analytical models which can consider both mean stress and VA loading sequence effect were developed for better prediction of the fatigue life. Good agreement is observed between predictions and test results.